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Table 2 Effect of CPC incubation time on TB culture recovery

From: Preservation of sputum samples with cetylpyridinium chloride (CPC) for tuberculosis cultures and Xpert MTB/RIF in a low-income country

Culture grading (WHO)

Non-CPC

CPC incubation time

n (%)

 

7 days

14 days

 

21 days

Contaminated

9 (18)

6 (12)

6 (12)

3 (6)

Negative

8 (16)

2 (4)

1 (2)

6 (12)

Positive

33 (66)

42 (84)

43 (86)

41 (82)

 < 20 colonies

0 (0)

3 (6)

4 (8)

3 (6)

 1+

3 (6)

7 (14)

7 (14)

7 (14)

 2+

10 (20)

13 (26)

13 (26)

15 (30)

 3+

20 (40)

19 (38)

19 (38)

16 (32)

Total

50 (100)

50 (100)

50 (100)

50 (100)

  1. Decontamination time of 15 min for all CPC treated samples before culture step
  2. Difference between non-CPC and CPC incubation time (7, 14 and 21 days) according to WHO culture grading (contaminated, negative, positive): p = 0.077 across groups (Fisher’s exact test)
  3. Culture results of 50 sputum samples not pretreated (non-CPC) or pretreated with CPC before processing (CPC), with varying CPC incubation time of 7, 14, and 21 days
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BMC Infectious Diseases

ISSN: 1471-2334

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